Read below for the actual license but the gist is that you can use the illustrations in any project, commercial or personal without attribution or any costs. Just don’t try to replicate ManyPixels, redistribute in packs the illustrations or create integrations for it.
If you are working on something and want to use illustrations to improve its appearance, modified or not, without the need for attribution or cost, you are good to go. If you find ManyPixels or its illustrations to be in the center of what you are doing (e.g. sell or re-distribute one/some of them, add them in an app), then you probably should not proceed.
Copyright 2023 MANYPIXELS PTE LTD
All images, assets and vectors published on ManyPixels can be used for free. You can use them for noncommercial and commercial purposes. You do not need to ask permission from or provide credit to the creator or ManyPixels.
More precisely, ManyPixels grants you an nonexclusive, worldwide copyright license to download, copy, modify, distribute, perform, and use the assets provided from ManyPixels for free, including for commercial purposes, without permission from or attributing the creator or ManyPixels. This license does not include the right to compile assets, vectors or images from ManyPixels to replicate a similar or competing service, in any form or distribute the assets in packs or otherwise. This extends to automated and non-automated ways to link, embed.